MPAndroidChart - Show MarkerView on long click

Question

I have CustomMarkerView with PieChart on MPAndroidChart, however I want to show the marker only when the chart is longClicked.

Is there any way I can achieve this result ?

Answer 1

Yes of course. I rebuilded this project from github. The first hint was from this post. You inherit your PieChart or every chart you want and apply a onTouchEvent on it. You create a class called ChartMarkerView and extends it's MarkerView. There you bind a view and set the duration of the ClickTime.

Hope it will help you to approach your target!

Update:

In addition to the part above @AinulBedjo found out that you can reach the long click with @Override the draw method then only draw when the longClicked is true:

public class CustomPieChart extends PieChart {
    public CustomPieChart(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    final GestureDetector gestureDetector = new GestureDetector(new GestureDetector.SimpleOnGestureListener() {
        public void onLongPress(MotionEvent e) {
            CustomMarker markerView = (CustomMarker) getMarker();
            isLongClicked = true;

            //get angle and index of dataset
            float angle = getAngleForPoint(e.getX(), e.getY());
            int indexForAngle = getIndexForAngle(angle);

            // takes index of angle, Y-Position and dataSetIndex of 0
            Highlight highlight = new Highlight(indexForAngle, e.getY(), 0);
            highlightValue(highlight);

            // redraw
            invalidate();
        }

        @Override
        public boolean onSingleTapUp(MotionEvent e) {
            isLongClicked = false;
            return super.onSingleTapUp(e);
        }
    });

    Boolean isLongClicked = false;

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        boolean handled = true;
        // if there is no marker view or drawing marker is disabled
        if (isShowingMarker() && this.getMarker() instanceof CustomMarker){
            gestureDetector.onTouchEvent(event);
        }
        handled = super.onTouchEvent(event);
        return handled;
    }

    // draw markers on highlighter values
    @Override
    protected void drawMarkers(Canvas canvas) {
        // if there is no marker view or drawing marker is disabled
        if (mMarker == null || !isDrawMarkersEnabled() || !valuesToHighlight())
            return;

        for (Highlight highlight : mIndicesToHighlight) {

            IDataSet set = mData.getDataSetByIndex(highlight.getDataSetIndex());

            Entry e = mData.getEntryForHighlight(highlight);
            int entryIndex = set.getEntryIndex(e);

            // make sure entry not null
            if (e == null || entryIndex > set.getEntryCount() * mAnimator.getPhaseX())
                continue;

            float[] pos = getMarkerPosition(highlight);

            // check bounds
            if (!mViewPortHandler.isInBounds(pos[0], pos[1]))
                continue;

            // callbacks to update the content
            mMarker.refreshContent(e, highlight);

            // draw the marker
            if (isLongClicked) {
                mMarker.draw(canvas, pos[0], pos[1]);
            }
        }
    }

    private boolean isShowingMarker(){
        return mMarker != null && isDrawMarkersEnabled();
    }
}